Analysis of the water quality condition of the Zijiang River in summer and the applicability of evaluation methods

¹ Yichang Dongfengqu Irrigation Area Administration, China
² College of Hydraulic and Environmental Engineering, China Three Gorges University
³ China Institute of Water Resources and Hydropower Research

^* Author: T.Zhang, mainly engaged in the management and research of water conservancy and water ecology. Corresponding author: S.J.Zhu, PhD, associate professor, Email: 46212465@qq.com.

Abstract

The single-factor evaluation method, improved Nemerow index method, fuzzy mathematical synthesis evaluation method and comprehensive nutrient status index method were used to evaluate the water quality of the Zijiang River in summer, and to analyze the applicability of the evaluation methods. The results show that: (1) The Zijiang River is heavily polluted with nitrogen and TN is the main pollutant in the summer. The overall nutrient status index is 34.33, which is not eutrophic. (2) The single-factor evaluation method is simple and suitable for rapid identification of excessive pollutants, but cannot reflect the water quality. the Nemerow index method takes into account the weight of each evaluation factor in the river water quality, and is suitable for making a comprehensive evaluation of the river water quality, but has a certain degree of subjectivity when classifying the water quality. The fuzzy comprehensive evaluation method is suitable for reflecting the influence of different evaluation factors on water quality by calculating the weight and membership degree of each evaluation factor, but the calculation is complicated.The Integrated Nutrient Status Index method is suitable for determining whether eutrophication is occurring in a water body and cannot determine the water quality category.